Supplemental data path for supporting on-screen displays from external sources in a monitor/TV receiver using a secondary analog signal path

ABSTRACT

An external source outputs an analog signal containing on-screen information (OSD) for the external source, which has been decoded in the external source, and an encoded high definition digital signal. A high definition television (HDTV) has separate inputs for the analog signal and the high definition digital signal, which is decoded in the HDTV to a format suitable for display on the HDTV monitor. Accordingly, both the OSD information for the external source and the high definition signal are available for use and display on the HDTV monitor.

BACKGROUND

[0001] 1. Field of the Invention

[0002] This invention relates to television systems and, in particular,to such systems for displaying on-screen display (OSD) information froman external source.

[0003] 2. Description of Related Art

[0004] Television systems receive signals from a variety of sources fordisplaying the signals on television monitors. Conventional televisionsignals are analog and are typically sent directly to the televisionreceiver via cable, satellite, or terrestrial transmissions using analogstandards such as NTSC, PAL, and SECAM. However, as the number ofdifferent types of signal sources increases, external devices coupled tothe television are needed to receive the signal and transmit the signalto television receiver. These external devices can include set-top boxes(STBs), video cassette recorders (VCRs), satellite dishes, and cableboxes for receiving signals from transmission methods such as directsatellite service (DSS), microwave broadcast, cellular television(“wireless cable”), and television delivered via digital telephone phonelines.

[0005] Such transmission methods allow consumers to receive a variety ofentertainment and information services on their television sets. Forexample, a consumer may receive a basic selection of programs, orspecial premium channel programs may be chosen for an additional charge.Information services such as stock prices, teletext for the hearingimpaired and others, or weather forecasts may also be received anddisplayed on the television monitor.

[0006] For the television monitor to be able to display these signals,the STB (which will be used throughout the description to represent anyexternal device for receiving and transmitting signals to thetelevision) demodulates and decodes the signal to an acceptable analogformat, such as NTSC. Typically, the STB outputs a composite analogsignal, which also contains on-screen display (OSD) information from thedevice. The OSD information is displayed on the television monitor foroperation of the STB. Using information from the OSD, the viewer cantune to specific channels from the STB, adjust parameters such aspicture intensity, contrast, or color tone, or control a peripheraldevice such as a VCR.

[0007] The OSD information is typically generated by a CPU within theSTB. When the input from a TV monitor is switched to the external outputof the STB, the OSD of the STB is available and visible on the TVdisplay monitor because all displays have the same aspect ratio (e.g.,4:3) and scanning format (e.g., NTSC) so that the OSD signal iscompatible with the display on the TV monitor.

[0008] More recently, signals are also being transmitted digitally, suchas in standard definition (SD) by Digital Satellite System (DSS).Digital signals are encoded according to an MPEG (Moving Picture ExpertGroup) standard, transmitted, and received by an appropriate STB coupledto a television monitor. The STB device, such as a DSS receiver, digitalcable box, or DVD recorder, contains a standard, main-level MPEG decoderfor decoding the SD digital signal into SD analog signal, e.g., NTSC.The SD analog signal is superimposed with the OSD signal generated bythe CPU within the STB. The resulting analog signal is transmitted fromthe STB output to the input of a television monitor, where the OSDinformation is extracted from the signal for display on the televisionmonitor. Consequently, operation of the STB, such as to navigate throughchannels in the STB, is possible because the SD digital signal has beendecoded and merged with the OSD information in an analog signal format,which is compatible with the television monitor (i.e., 4:3 aspect ratio,NTSC scanning standard, etc.).

[0009] However, the MPEG decoders in current STBs are unable to decodehigh definition (HD) digital signals. Thus, a STB will typicallydemodulate and pass the HD signal in digital form to the input of a highdefinition television (HDTV), typically through a high speed digitalinterface, such as the IEEE 1394 interface. A high-level MPEG-2 decoderinside the HDTV will then decode the HD digital signal for display onthe television monitor, which displays a 16:9 aspect ratio pictureinstead of the conventional 4:3 aspect ratio standard definitionpicture. However, the OSD information for the STB generated by the STBCPU is still in analog form. Furthermore, the STB does not know theon-screen display (OSD) capability, the aspect ratio, or native displayscanning format of the television monitor. Thus, the analog OSDinformation cannot be included with the HD signal in the digitaltransport stream to the monitor. As a result, no OSD information isavailable to the HDTV, and operation of the STB is not possible.

[0010] One possible solution for providing OSD information to HDTVs isto include a high-level MPEG-2 decoder in the STB. The HD digitalsignals being received by the STB can then be decoded by the MPEG-2decoder and superimposed with the internally generated OSD information.The resulting signal, with OSD information, can then be sent to theHDTV. However, one significant problem is that this signal has a veryhigh transmission bandwidth, which cannot be transmitted practicallywith current interfaces, such as the IEEE 1394. Therefore, beforetransmission, the decoded signal with OSD information can be encoded andcompressed with a high-level MPEG-2 encoder in the STB to reduce thetransmission bandwidth. This approach is very cost prohibitive due tothe need for a high-level MPEG-2 decoder and encoder in the STB,particularly since HD digital broadcasts are in their infancy and fewprograms are being transmitted in the HD digital format. Furthermore,televisions capable of displaying high definition digital picturescurrently constitute only a small percentage of the televisions in usetoday. Consequently, STB manufacturers are reluctant to buildhigh-priced STBs with high-level decoding capabilities because only asmall percentage of televisions would utilize this feature. Thus,current HDTVs have high-level MPEG-2 decoders built into the televisionfor decoding the high definition digital signals received from the STBsin order to display the high definition images.

[0011] However, as mentioned above, the high definition signal cominginto the television is digital, while the OSD information for the STB isanalog. As a result, the OSD information for the STB is incompatiblewith the HDTV, thereby rendering the STB on-screen display informationinoperable with the HDTV display.

[0012] Accordingly, it is desirable for a high definition television tobe able to display and utilize analog on-screen information from aset-top box without greatly increasing the cost to the televisionsystem.

SUMMARY

[0013] In accordance with an aspect of the invention, a method andsystem are provided which allows the on-screen display (OSD) informationfrom a set-top box (STB) or other external display device to bedisplayed on a high definition television (HDTV) by transmittingseparate signals for the digital high definition image and for theanalog OSD information for the STB to the HDTV and by processing the OSDinformation in the STB and the high definition signal in the HDTV.

[0014] The high definition digital signal is demodulated anddemultiplexed in the STB and then transmitted out of the STB via a highspeed digital interface, such as IEEE1394. Also, OSD information for theSTB is generated within the STB. The OSD information is decoded andconverted to an analog signal and transmitted out of the STB via ananalog interface. The HD digital signal and the analog OSD signal aresent to a digital input and an analog input, respectively, of the HDTV.Within the HDTV, a high-level MPEG-2 decoder decodes the HD digitalsignal for display on the HDTV monitor. However, when the OSDinformation for the STB is needed, the HDTV switches the display inputto the analog signal carrying the STB OSD information. The OSDinformation is displayed along with or instead of the HD video display.When the OSD information is displayed, the user can access the STB viathe on-screen information.

[0015] In other embodiments, the OSD information for the STB istransmitted out of the STB along the digital transport stream, alongwith the HD digital data, via a high speed digital interface, such asIEEE1394. The HDTV demultiplexes and decodes the digital transportstream to extract the OSD information for display on the HDTV monitor.Thus, functions in the STB can be accessed from the displayed OSDinformation.

[0016] The present invention will be more fully understood uponconsideration of the detailed description below, taken together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a block diagram of a high definition television (HDTV)system in accordance with one embodiment of the present invention;

[0018]FIG. 2 is a block diagram of a set-top box (STB) for the HDTVsystem of FIG. 1;

[0019]FIG. 3 is a block diagram of a HDTV monitor/receiver for the HDTVsystem of FIG. 1;

[0020]FIGS. 4A and 4B are diagrams of STB OSD information displays onthe screen of the HDTV; and

[0021]FIG. 5 is a block diagram of another embodiment of the STB for theHDTV system of FIG. 1.

[0022] Use of the same reference symbols in different figures indicatessimilar or identical items.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] In accordance with the present invention, a high definitiontelevision (HDTV) system includes an HDTV receiver/monitor coupled to aset-top box (STB), where the STB refers to any external signal sourcefor the HDTV, such as a digital cable box, a digital video disc (DVD)player, etc. The STB has separate digital and analog outputs. Thedigital output supplies, to a digital input of the HDTV, a digitaltransport stream containing the high definition signal to be displayedon the HDTV monitor. The analog output supplies on-screen display (OSD)information for the STB, which is generated and decoded within the STB,to an analog input of the HDTV. Thus, when an OSD signal is availablefor use and display on the HDTV monitor, the HDTV switches the monitor'ssignal source to the analog input, thereby allowing the HDTV to displayand utilize the OSD of the STB, such as for channel navigation.

[0024]FIG. 1 shows a general block diagram of a high definitiontelevision system according to one embodiment of the present invention.A set-top box (STB) 100 has a digital output terminal 110 for supplyingdigital signals to a high definition television (HDTV) receiver/monitor120 and an analog output terminal 130 for supplying analog signals tothe HDTV 120 for display on a screen 140 of the HDTV 120. The STB 100receives high definition (HD) digital signals, for example, which havebeen encoded or compressed according to a high-level MPEG-2 standard.The digital output terminal 110 of the STB 100 is coupled to a digitalinput terminal 150 of the HDTV 120 via a high-speed digital transport160, such as the IEEE 1394 interface, which allows the high-level MPEG-2encoded signal to be transmitted to the HDTV 120. STB 100 also generatesanalog on-screen display (OSD) information and transmits the analogsignal carrying the OSD information to an analog input terminal 170 ofthe STB 100. The analog input terminal 170 of the STB 100 is coupled tothe analog output terminal 130 of the HDTV 120 via a suitable analogtransport 180. The HDTV 120 includes a high-level MPEG-2 decoder fordecoding the received HD digital signals so that high definition imagescorresponding to the HD digital signals can be displayed on the monitorof the HDTV 120. By having separate analog and digital inputs, with theanalog input providing OSD information from the STB 100 and the digitalinput providing HD digital signals, the HDTV 120 can utilize the OSDinformation from the STB 100 by switching from one input to another asdesired.

[0025]FIG. 2 shows a more detailed block diagram of the STB 100. STB 100includes a terminal 210 for receiving the high-level MPEG-2 encodedsignal. This signal is demodulated by a front-end demodulator 220 torecover the original information and then sent to a transport unit 230.The output of the demodulator 220 is often referred to as a transportstream (TS), which is a multiplexed signal of several individual datastreams. Each data stream is identifiable via a unique packetidentification (PID) number. The TS is then sent to the transport unit230, where the TS is demultiplexed into individual video and audiodigital streams.

[0026] However, the user may only need a few of the many differentindividual data streams contained in a single TS. A CPU 240, which mayalso be embedded within the transport unit 230, receives informationfrom the user as to which data streams are to be extracted for use. TheCPU 240, based on the unique PID numbers, extracts the desiredindividual data streams for further processing.

[0027] The desired data stream from transport unit 230, as selected byCPU 240, can then be routed to various destinations, such as amain-level MPEG-2 decoder 250 for conventional standard definitiondecoding and to the digital output terminal 110 for transmission to theHDTV. OSD information for the STB is generated by CPU 240. If the signalcontaining the OSD information is compatible with MPEG-2 decoder 250,then the signal is transmitted directly to MPEG-2 decoder 250 fordecoding. However, if the signal is not compatible with MPEG-2 decoder250, the signal is sent to a video encoder 260 for transforming theoutput signal from CPU 240 to a format which is compatible with MPEG-2decoder 250 before being transmitted to decoder 250.

[0028] The input signal to MPEG-2 decoder 250, either from CPU 240 orvideo encoder 260, is a digital MPEG-encoded stream. The MPEG stream isdecoded and uncompressed by main-level MPEG-2 decoder 250 to restore thesignal to its original digital format. After decoding, adigital-to-analog converter (DAC) within MPEG-2 decoder 250 converts thedigital signal to an analog signal for transmission through analogoutput terminal 130 of the STB. Thus, an analog signal containing OSDinformation is available at the analog output terminal 130 of the STB100, while a digital signal containing encoded high definition data isavailable at the digital output terminal 110 of the STB 100.

[0029]FIG. 3 shows a more detailed block diagram of HDTV 120, which hasdigital input terminal 150 for receiving the digital HD data from theSTB 100 and analog input terminal 170 for receiving the analog OSDinformation from the STB 100. HDTV 120 includes a terminal 310 forreceiving a digital signal, such as an 8-level vestigial sideband (VSB)signal from a terrestrial transmission. This digital signal isdemodulated by a front-end demodulator 320 and transmitted to aconditional access unit 330 for decryption of the input transportstream. Conditional access unit 330 can be configured to allow usersvarying degrees of access to the transport stream by only decrypting thetransport stream or portions thereof based on authorization codessupplied by the user. For example, if PID information is encrypted inthe transport stream, a transport unit 340 (and a CPU 350) will beunable to locate and extract individual data streams from the transportstream without first being decrypted by a user with the properauthorization code. In other instances, the individual video and audiodata streams can be encrypted so that access is denied to the dataunless the user supplies proper authorization codes. However, if accessto the data is to be unconditional, conditional access unit 330 can beeliminated so that output signals from demodulator 320 are transmitteddirectly to transport unit 340.

[0030] The signal from the conditional access unit 330 (or fromdemodulator 320) and the HD digital signal from the STB are sent totransport unit 340. As with the STB, transport unit 340 demultiplexesthe transport stream, and CPU 350 (either embedded within or external totransport unit 340) accesses the desired data stream within thetransport stream based on the PID number. In addition, CPU 350 receivesthe signal from the transport unit 340 and generates OSD information forthe HDTV 120. A high-level MPEG-2 decoder 360 receives the signal fromthe transport unit 340, which contains the encoded HD digital signal,and decodes the signal so that the format is suitable for display on themonitor of the HDTV, as is well known to those in the art. Thehigh-level MPEG-2 decoder 360 can be located within the HDTV orcontained in a unit outside the HDTV, such as in a set-back box.

[0031] Also included in the HDTV 120 is a video switching device 370,which receives signals from CPU 350, high-level MPEG-2 decoder 360, andanalog input terminal 170. Switching device 370 selects or combinesvideo signals and routes the desired signal to a cathode ray tube (CRT)380 for displaying the image or images on the HDTV monitor. For example,switching device 370 can select between the video signal (fromhigh-level MPEG-2 decoder 360) and the OSD signal (from CPU 350 or fromanalog input terminal 170 from the STB), or switching device 370 canmerely superimpose the OSD signal onto the video signal. Other types ofswitching device 370 can overlay the OSD signal onto the video signalwith varying degrees of transparency, such that the video display in thebackground is partially visible through a semi-transparent OSD display.In the case where the video and OSD signals are simply superimposed, aninexpensive CMOS switch can be used if the signal bandwidth is not verylarge. However, in the case of variable transparency, an alpha blendingcircuit is required which is much more complicated. For typicaloperation of the HDTV, the switching device 370 selects high-levelMPEG-2 decoded signals to display high definition 16:9 aspect ratioimages and occasionally selects OSD information for the HDTV whenneeded, such as when selected by the viewer through a remote controller.The OSD information for the HDTV can be displayed by itself orconcurrently with the high definition image signals.

[0032] When OSD information for the STB 100 is needed, the switchingdevice 370 routes the analog signal at the analog input terminal 170containing the STB OSD information to the CRT 380. Selection of theanalog signal can be carried out by an auto-detect function built intothe HDTV, such as in the switching device 370, or by sensing thepresence of the OSD information via a superimposed DC level on thechroma signal or in the digital transport stream. A universal languagecapable of communicating the OSD information of the STB 100 is used toconvey the information via the digital transport stream to the transportunit 340 in the TV receiver/monitor 120. Some suitable languages forconveying OSD information include MHEG, PDG, HTML, VRML, and Java.

[0033] An external trigger, which could be sent in the serial digitalstream from the STB or via a control signal superimposed on the analogsignal from the STB, indicates to switching device 370 whether to switchto the video generated from the digital stream or to the OSD that isinputted via analog input terminal 170. For example, auxiliary data inthe digital transport stream can serve as the external trigger so thatthe TV receiver/monitor 120 can receive indication from the STB 100 thatan OSD signal is available and valid and needs to be displayed. Theauxiliary data is extracted from the transport stream in the transportunit 340. The extracted auxiliary data is then processed by CPU 350,which may be embedded in or external to transport unit 340. Based on theprocessed data, CPU 350 indicates to switching device 370 whether toswitch to the OSD display for the HDTV, the OSD display from the STB, orthe video signal.

[0034] When the OSD of the STB is being displayed, a remote controllerfor controlling functions of both the STB and the HDTV can be used tospecifically control the STB, e.g., the channels of the STB. The remotecontroller can be switched to the STB using various methods, such as bypressing a key on the remote controller whenever operation of the STB isdesired and pressing another key to switch control back to the HDTV.Another method might be to include circuitry in the HDTV to detect thepresence or absence of an OSD display. Then, when the OSD of an externalsource is being displayed, the function of the remote control can beautomatically interpreted by the HDTV and translated to the appropriateSTB commands, such as the channel up-down keys. For example, typicallywhen the OSD of a known STB is being displayed, the OSD information hasbeen requested by the user in order to access some function or featureof the STB. Thus when the OSD for the STB is being displayed, thenominally TV orientated keys of the remote control unit can beinterpreted by the HDTV as being commands meant for the STB.Specifically, keys which are common to both the STB and the HDTV can beused to access functions of the STB. Channel up/down keys, number keys(0-9), and the menu keys (e.g., menu, cursor up/down/left/right, enter)are some of the common keys that can be used for both the HDTV and theSTB.

[0035] In another embodiment, a multi-image processor 390 is coupledbetween the analog input terminal 170 of the HDTV and the videoswitching device 370. Processor 390 receives the analog OSD informationfrom the STB 100 and creates image signals from the analog OSDinformation signal for displaying the OSD information of the STB on themonitor of the HDTV. Multi-image processor 390, such as a “Multi-ImageDrive” (MID) in the Sony domestic Japanese television model KV-32HDF9,is capable of converting one signal format to another using any ofseveral input and output signal formats. Thus, the OSD information canbe displayed as a picture-in-picture (PIP) (shown in FIG. 4A),picture-out-of-picture (POP) (shown in FIG. 4B), or any other displaytype that can be formatted by the multi-image processor 390. In FIG. 4A,the OSD information is displayed in a sub-window 400 within the mainpicture 410, and in FIG. 4B, the OSD information is displayed in asplit-window 420 separate from the main picture 430.

[0036] When OSD information for the STB is no longer available orneeded, video switching device 370 switches the signal source to the CRT390 back to the CPU 350 and/or the high-level MPEG-2 decoder 360.

[0037] In another embodiment, OSD information from the STB can beextracted from the digital transport stream, instead of a separateanalog signal. In FIG. 5, a STB 500 includes similar components as STB100 of FIG. 2, except that main-level MPEG-2 decoder 250 does notperform a digital-to-analog conversion. In this embodiment, thedigitally decoded signal from MPEG-2 decoder 250 containing the OSDinformation of the STB is sent along the same digital transport streamas the output signal from transport unit 230. Thus, the STB's OSD datais carried out of digital output terminal 110 and into the serialdigital input terminal 150 (FIG. 3) for demultiplexing in transport unit340. The signal containing the OSD information is then transmitted toCPU 350, and according to pre-programmed instructions, CPU 350reconstructs the OSD information and constructs a data base containingavailable programs the OSD information. In the case that the data fromthe transport stream contains graphical information, such as HTML orMHEG, a graphical language decoder contained in CPU 350 decodes thesignal prior to use by the CPU. The resulting signal is sent toswitching device 370, where the OSD information can be selected fordisplay via CRT 380.

[0038] Although the invention has been described with reference toparticular embodiments, the description is only an example of theinvention's application and should not be taken as a limitation.Consequently, various adaptations and combinations of features of theembodiments disclosed are within the scope of the invention as definedby the following claims.

We claim:
 1. A method of displaying information from an external sourceon a monitor of a high definition television (HDTV), comprising:generating on-screen display (OSD) information in the external source;converting the OSD information to an analog signal; transmitting theanalog signal to the HDTV along an analog interface; processing theanalog signal in the HDTV; and displaying the analog signal containingthe OSD information for the external source on the monitor of the HDTV.2. The method of claim 1, wherein the external source is a set-top box.3. The method of claim 1, further comprising: transmitting a highdefinition (HD) digital signal from the external source to the HDTV viaa digital interface; decoding the HD digital signal in the HDTV; anddisplaying a video representation of the HD digital signal.
 4. Themethod of claim 3, wherein the digital interface is an IEEE1394interface.
 5. The method of claim 3, wherein the decoding is with ahigh-level MPEG-2 decoder.
 6. The method of claim 3, further comprisingselecting the analog signal when OSD information is desired for displayand selecting the HD digital signal when a video is desired for display.7. The method of claim 6, wherein the selecting is with an externalcontrol device.
 8. The method of claim 6, wherein the selecting is basedon information contained in the signals from the external source.
 9. Themethod of claim 3, wherein the OSD information and the video aredisplayed at the same time.
 10. The method of claim 3, wherein the OSDinformation and the video are displayed at different times.
 11. A systemfor displaying information on a monitor, comprising: an external sourcehaving a high definition digital input terminal for accepting a highdefinition digital transport stream, a high definition digital outputterminal for outputting high definition digital signals, and an analogoutput terminal for outputting an analog signal containing on-screendisplay (OSD) information for the external source; and a high definitiontelevision (HDTV) having a digital input terminal for accepting the highdefinition digital signals and an analog input terminal for acceptingthe analog signal containing OSD information.
 12. The system of claim11, wherein the external source is a set-top box.
 13. The system ofclaim 11, wherein the external source comprises: a central processingunit (CPU) for generating the OSD information; and a decoder coupledbetween the CPU and the analog output terminal for transforming the OSDinformation to an analog format.
 14. The system of claim 13, wherein thedecoder is a main-level MPEG-2 decoder.
 15. The system of claim 13,wherein the external source further comprises: a demodulator coupled tothe high definition digital input terminal for demodulating the digitaltransport stream; and a transport unit coupled between the demodulatorand the digital output terminal for selecting desired signals from thedigital transport stream.
 16. The system of claim 11, wherein the HDTVcomprises: a high-level decoder coupled to the digital input terminalfor decoding the high definition digital signals; and a video switchingdevice coupled to the high-level decoder and the analog input terminalfor selecting a high definition digital signal or the analog signalcontaining the OSD information.
 17. The system of claim 16, wherein thehigh-level decoder is a high-level MPEG-2 decoder.
 18. The system ofclaim 11, further comprising a remote control unit for selecting thehigh definition digital signals or the analog signal containing the OSDinformation for display on the monitor.
 19. The system of claim 16,wherein the HDTV further comprises a CPU coupled to the video switchingdevice for generating OSD information for the HDTV.
 20. The system ofclaim 16, further comprising a digital interface coupling the digitaloutput terminal of the external source to the digital input terminal ofthe HDTV, and an analog interface coupling the analog output terminal ofthe external source to the analog input terminal of the HDTV.
 21. Thesystem of claim 20, wherein the digital interface is an IEEE1394interface.
 22. A method of displaying information from an externalsource on a monitor of a high definition television (HDTV), comprising:generating on-screen display (OSD) information in the external source;transmitting the OSD information to the HDTV along a digital transportstream; processing the digital transport stream in the HDTV to extractthe OSD information from the digital transport stream; and displayingthe OSD information for the external source on the monitor of the HDTV.23. The method of claim 22, wherein the processing comprisesdemodulating and decoding the digital transport stream.
 24. The methodof claim 22, wherein the transmitting is via a high speed digitalinterface.
 25. The method of claim 24, wherein the high speed digitalinterface is an IEEE1394 interface.
 26. The method of claim 22, furthercomprising transmitting a high definition (HD) digital signal along withthe OSD information along the digital transport stream.
 27. The methodof claim 23, wherein the external source is a set-top box.